1. Field of the Invention
This invention relates to printing and especially to a method and apparatus for printing with an ink jet. While not necessarily limited thereto, the invention has particular application to serial printers.
2. Description of the Prior Art
Multi-nozzle ink jet printers are well-known. A stream of ink in the form of uniformly-spaced drops is projected from each nozzle toward a print medium while a relative motion is effected between the nozzle and record medium. In one type of multi-nozzle jet printer, such as shown in U.S. Pat. No. 3,298,030, issued to A. M. Lewis et al on Jan. 10, 1967, a nozzle is provided for each line of characters and the individual drops are deflected transverse to the direction of relative motion for a distance equal at least to the length of the stroke of a matrix pattern corresponding to the largest data symbol to be recorded. The time required to deflect the streams over the entire character height tends to limit the printing rate. In another type of multi-nozzle printer a row of nozzles is provided for each spot, i.e., dot position in the stroke of the character matrix, see for example, U.S. Pat. Nos. 3,373,437, issued to R. G. Sweet et al on Mar. 12, 1968 and 3,560,641, issued to R. P. Taylor et al on Feb. 2, 1971.
In the nozzle per spot printer, packaging of the multiple nozzles within the space required for conventional character and dot sizes is a problem. Sweet et al deals with the problem by an arrangement which requires convergent beams. This can present problems in aiming. Taylor et al also recognizes the problem and provides a solution in the form of multiple arrays separated in staggered formation along the path of travel of the medium. Alignment of the multiple arrays and timing requirements can be quite complex.